Andrii Nakryiko says:
====================
bpf-next 2021-12-10 v2
We've added 115 non-merge commits during the last 26 day(s) which contain
a total of 182 files changed, 5747 insertions(+), 2564 deletions(-).
The main changes are:
1) Various samples fixes, from Alexander Lobakin.
2) BPF CO-RE support in kernel and light skeleton, from Alexei Starovoitov.
3) A batch of new unified APIs for libbpf, logging improvements, version
querying, etc. Also a batch of old deprecations for old APIs and various
bug fixes, in preparation for libbpf 1.0, from Andrii Nakryiko.
4) BPF documentation reorganization and improvements, from Christoph Hellwig
and Dave Tucker.
5) Support for declarative initialization of BPF_MAP_TYPE_PROG_ARRAY in
libbpf, from Hengqi Chen.
6) Verifier log fixes, from Hou Tao.
7) Runtime-bounded loops support with bpf_loop() helper, from Joanne Koong.
8) Extend branch record capturing to all platforms that support it,
from Kajol Jain.
9) Light skeleton codegen improvements, from Kumar Kartikeya Dwivedi.
10) bpftool doc-generating script improvements, from Quentin Monnet.
11) Two libbpf v0.6 bug fixes, from Shuyi Cheng and Vincent Minet.
12) Deprecation warning fix for perf/bpf_counter, from Song Liu.
13) MAX_TAIL_CALL_CNT unification and MIPS build fix for libbpf,
from Tiezhu Yang.
14) BTF_KING_TYPE_TAG follow-up fixes, from Yonghong Song.
15) Selftests fixes and improvements, from Ilya Leoshkevich, Jean-Philippe
Brucker, Jiri Olsa, Maxim Mikityanskiy, Tirthendu Sarkar, Yucong Sun,
and others.
* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (115 commits)
libbpf: Add "bool skipped" to struct bpf_map
libbpf: Fix typo in btf__dedup@LIBBPF_0.0.2 definition
bpftool: Switch bpf_object__load_xattr() to bpf_object__load()
selftests/bpf: Remove the only use of deprecated bpf_object__load_xattr()
selftests/bpf: Add test for libbpf's custom log_buf behavior
selftests/bpf: Replace all uses of bpf_load_btf() with bpf_btf_load()
libbpf: Deprecate bpf_object__load_xattr()
libbpf: Add per-program log buffer setter and getter
libbpf: Preserve kernel error code and remove kprobe prog type guessing
libbpf: Improve logging around BPF program loading
libbpf: Allow passing user log setting through bpf_object_open_opts
libbpf: Allow passing preallocated log_buf when loading BTF into kernel
libbpf: Add OPTS-based bpf_btf_load() API
libbpf: Fix bpf_prog_load() log_buf logic for log_level 0
samples/bpf: Remove unneeded variable
bpf: Remove redundant assignment to pointer t
selftests/bpf: Fix a compilation warning
perf/bpf_counter: Use bpf_map_create instead of bpf_create_map
samples: bpf: Fix 'unknown warning group' build warning on Clang
samples: bpf: Fix xdp_sample_user.o linking with Clang
...
====================
Link: https://lore.kernel.org/r/20211210234746.2100561-1-andrii@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
The pointer t is being initialized with a value that is never read. The
pointer is re-assigned a value a littler later on, hence the initialization
is redundant and can be removed.
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211207224718.59593-1-colin.i.king@gmail.com
When CONFIG_DEBUG_INFO_BTF_MODULES is not set
the following warning can be seen:
kernel/bpf/btf.c:6588:13: warning: 'purge_cand_cache' defined but not used [-Wunused-function]
Fix it.
Fixes: 1e89106da2 ("bpf: Add bpf_core_add_cands() and wire it into bpf_core_apply_relo_insn().")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211207014839.6976-1-alexei.starovoitov@gmail.com
BPF_LOG_KERNEL is only used internally, so disallow bpf_btf_load()
to set log level as BPF_LOG_KERNEL. The same checking has already
been done in bpf_check(), so factor out a helper to check the
validity of log attributes and use it in both places.
Fixes: 8580ac9404 ("bpf: Process in-kernel BTF")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20211203053001.740945-1-houtao1@huawei.com
When module registering its set is built-in, THIS_MODULE will be NULL,
hence we cannot return early in case owner is NULL.
Fixes: 14f267d95f ("bpf: btf: Introduce helpers for dynamic BTF set registration")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211122144742.477787-3-memxor@gmail.com
Vinicius Costa Gomes reported [0] that build fails when
CONFIG_DEBUG_INFO_BTF is enabled and CONFIG_BPF_SYSCALL is disabled.
This leads to btf.c not being compiled, and then no symbol being present
in vmlinux for the declarations in btf.h. Since BTF is not useful
without enabling BPF subsystem, disallow this combination.
However, theoretically disabling both now could still fail, as the
symbol for kfunc_btf_id_list variables is not available. This isn't a
problem as the compiler usually optimizes the whole register/unregister
call, but at lower optimization levels it can fail the build in linking
stage.
Fix that by adding dummy variables so that modules taking address of
them still work, but the whole thing is a noop.
[0]: https://lore.kernel.org/bpf/20211110205418.332403-1-vinicius.gomes@intel.com
Fixes: 14f267d95f ("bpf: btf: Introduce helpers for dynamic BTF set registration")
Reported-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20211122144742.477787-2-memxor@gmail.com
Given BPF program's BTF root type name perform the following steps:
. search in vmlinux candidate cache.
. if (present in cache and candidate list >= 1) return candidate list.
. do a linear search through kernel BTFs for possible candidates.
. regardless of number of candidates found populate vmlinux cache.
. if (candidate list >= 1) return candidate list.
. search in module candidate cache.
. if (present in cache) return candidate list (even if list is empty).
. do a linear search through BTFs of all kernel modules
collecting candidates from all of them.
. regardless of number of candidates found populate module cache.
. return candidate list.
Then wire the result into bpf_core_apply_relo_insn().
When BPF program is trying to CO-RE relocate a type
that doesn't exist in either vmlinux BTF or in modules BTFs
these steps will perform 2 cache lookups when cache is hit.
Note the cache doesn't prevent the abuse by the program that might
have lots of relocations that cannot be resolved. Hence cond_resched().
CO-RE in the kernel requires CAP_BPF, since BTF loading requires it.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-9-alexei.starovoitov@gmail.com
Make BTF log size limit to be the same as the verifier log size limit.
Otherwise tools that progressively increase log size and use the same log
for BTF loading and program loading will be hitting hard to debug EINVAL.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-7-alexei.starovoitov@gmail.com
struct bpf_core_relo is generated by llvm and processed by libbpf.
It's a de-facto uapi.
With CO-RE in the kernel the struct bpf_core_relo becomes uapi de-jure.
Add an ability to pass a set of 'struct bpf_core_relo' to prog_load command
and let the kernel perform CO-RE relocations.
Note the struct bpf_line_info and struct bpf_func_info have the same
layout when passed from LLVM to libbpf and from libbpf to the kernel
except "insn_off" fields means "byte offset" when LLVM generates it.
Then libbpf converts it to "insn index" to pass to the kernel.
The struct bpf_core_relo's "insn_off" field is always "byte offset".
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-6-alexei.starovoitov@gmail.com
Make relo_core.c to be compiled for the kernel and for user space libbpf.
Note the patch is reducing BPF_CORE_SPEC_MAX_LEN from 64 to 32.
This is the maximum number of nested structs and arrays.
For example:
struct sample {
int a;
struct {
int b[10];
};
};
struct sample *s = ...;
int *y = &s->b[5];
This field access is encoded as "0:1:0:5" and spec len is 4.
The follow up patch might bump it back to 64.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-4-alexei.starovoitov@gmail.com
Rename btf_member_bit_offset() and btf_member_bitfield_size() to
avoid conflicts with similarly named helpers in libbpf's btf.h.
Rename the kernel helpers, since libbpf helpers are part of uapi.
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-3-alexei.starovoitov@gmail.com
Similar to btf_sock_ids, btf_tracing_ids provides btf ID for task_struct,
file, and vm_area_struct via easy to understand format like
btf_tracing_ids[BTF_TRACING_TYPE_[TASK|file|VMA]].
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211112150243.1270987-3-songliubraving@fb.com
LLVM patches ([1] for clang, [2] and [3] for BPF backend)
added support for btf_type_tag attributes. This patch
added support for the kernel.
The main motivation for btf_type_tag is to bring kernel
annotations __user, __rcu etc. to btf. With such information
available in btf, bpf verifier can detect mis-usages
and reject the program. For example, for __user tagged pointer,
developers can then use proper helper like bpf_probe_read_user()
etc. to read the data.
BTF_KIND_TYPE_TAG may also useful for other tracing
facility where instead of to require user to specify
kernel/user address type, the kernel can detect it
by itself with btf.
[1] https://reviews.llvm.org/D111199
[2] https://reviews.llvm.org/D113222
[3] https://reviews.llvm.org/D113496
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211112012609.1505032-1-yhs@fb.com
In some profiler use cases, it is necessary to map an address to the
backing file, e.g., a shared library. bpf_find_vma helper provides a
flexible way to achieve this. bpf_find_vma maps an address of a task to
the vma (vm_area_struct) for this address, and feed the vma to an callback
BPF function. The callback function is necessary here, as we need to
ensure mmap_sem is unlocked.
It is necessary to lock mmap_sem for find_vma. To lock and unlock mmap_sem
safely when irqs are disable, we use the same mechanism as stackmap with
build_id. Specifically, when irqs are disabled, the unlocked is postponed
in an irq_work. Refactor stackmap.c so that the irq_work is shared among
bpf_find_vma and stackmap helpers.
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Hengqi Chen <hengqi.chen@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211105232330.1936330-2-songliubraving@fb.com
Patch set [1] introduced BTF_KIND_TAG to allow tagging
declarations for struct/union, struct/union field, var, func
and func arguments and these tags will be encoded into
dwarf. They are also encoded to btf by llvm for the bpf target.
After BTF_KIND_TAG is introduced, we intended to use it
for kernel __user attributes. But kernel __user is actually
a type attribute. Upstream and internal discussion showed
it is not a good idea to mix declaration attribute and
type attribute. So we proposed to introduce btf_type_tag
as a type attribute and existing btf_tag renamed to
btf_decl_tag ([2]).
This patch renamed BTF_KIND_TAG to BTF_KIND_DECL_TAG and some
other declarations with *_tag to *_decl_tag to make it clear
the tag is for declaration. In the future, BTF_KIND_TYPE_TAG
might be introduced per [3].
[1] https://lore.kernel.org/bpf/20210914223004.244411-1-yhs@fb.com/
[2] https://reviews.llvm.org/D111588
[3] https://reviews.llvm.org/D111199
Fixes: b5ea834dde ("bpf: Support for new btf kind BTF_KIND_TAG")
Fixes: 5b84bd1036 ("libbpf: Add support for BTF_KIND_TAG")
Fixes: 5c07f2fec0 ("bpftool: Add support for BTF_KIND_TAG")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211012164838.3345699-1-yhs@fb.com
This adds selftests that tests the success and failure path for modules
kfuncs (in presence of invalid kfunc calls) for both libbpf and
gen_loader. It also adds a prog_test kfunc_btf_id_list so that we can
add module BTF ID set from bpf_testmod.
This also introduces a couple of test cases to verifier selftests for
validating whether we get an error or not depending on if invalid kfunc
call remains after elimination of unreachable instructions.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211002011757.311265-10-memxor@gmail.com
This commit moves BTF ID lookup into the newly added registration
helper, in a way that the bbr, cubic, and dctcp implementation set up
their sets in the bpf_tcp_ca kfunc_btf_set list, while the ones not
dependent on modules are looked up from the wrapper function.
This lifts the restriction for them to be compiled as built in objects,
and can be loaded as modules if required. Also modify Makefile.modfinal
to call resolve_btfids for each module.
Note that since kernel kfunc_ids never overlap with module kfunc_ids, we
only match the owner for module btf id sets.
See following commits for background on use of:
CONFIG_X86 ifdef:
569c484f99 (bpf: Limit static tcp-cc functions in the .BTF_ids list to x86)
CONFIG_DYNAMIC_FTRACE ifdef:
7aae231ac9 (bpf: tcp: Limit calling some tcp cc functions to CONFIG_DYNAMIC_FTRACE)
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211002011757.311265-6-memxor@gmail.com
This adds helpers for registering btf_id_set from modules and the
bpf_check_mod_kfunc_call callback that can be used to look them up.
With in kernel sets, the way this is supposed to work is, in kernel
callback looks up within the in-kernel kfunc whitelist, and then defers
to the dynamic BTF set lookup if it doesn't find the BTF id. If there is
no in-kernel BTF id set, this callback can be used directly.
Also fix includes for btf.h and bpfptr.h so that they can included in
isolation. This is in preparation for their usage in tcp_bbr, tcp_cubic
and tcp_dctcp modules in the next patch.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211002011757.311265-4-memxor@gmail.com
LLVM14 added support for a new C attribute ([1])
__attribute__((btf_tag("arbitrary_str")))
This attribute will be emitted to dwarf ([2]) and pahole
will convert it to BTF. Or for bpf target, this
attribute will be emitted to BTF directly ([3], [4]).
The attribute is intended to provide additional
information for
- struct/union type or struct/union member
- static/global variables
- static/global function or function parameter.
For linux kernel, the btf_tag can be applied
in various places to specify user pointer,
function pre- or post- condition, function
allow/deny in certain context, etc. Such information
will be encoded in vmlinux BTF and can be used
by verifier.
The btf_tag can also be applied to bpf programs
to help global verifiable functions, e.g.,
specifying preconditions, etc.
This patch added basic parsing and checking support
in kernel for new BTF_KIND_TAG kind.
[1] https://reviews.llvm.org/D106614
[2] https://reviews.llvm.org/D106621
[3] https://reviews.llvm.org/D106622
[4] https://reviews.llvm.org/D109560
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210914223015.245546-1-yhs@fb.com
This commit fixes linker errors along the lines of:
s390-linux-ld: task_iter.c:(.init.text+0xa4): undefined reference to `btf_task_struct_ids'`
Fix by defining btf_task_struct_ids unconditionally in kernel/bpf/btf.c
since there exists code that unconditionally uses btf_task_struct_ids.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/05d94748d9f4b3eecedc4fddd6875418a396e23c.1629942444.git.dxu@dxuuu.xyz
To avoid kernel build failure due to some missing .BTF-ids referenced
functions/types, the patch ([1]) tries to fill btf_id 0 for
these types.
In bpf verifier, for percpu variable and helper returning btf_id cases,
verifier already emitted proper warning with something like
verbose(env, "Helper has invalid btf_id in R%d\n", regno);
verbose(env, "invalid return type %d of func %s#%d\n",
fn->ret_type, func_id_name(func_id), func_id);
But this is not the case for bpf_iter context arguments.
I hacked resolve_btfids to encode btf_id 0 for struct task_struct.
With `./test_progs -n 7/5`, I got,
0: (79) r2 = *(u64 *)(r1 +0)
func 'bpf_iter_task' arg0 has btf_id 29739 type STRUCT 'bpf_iter_meta'
; struct seq_file *seq = ctx->meta->seq;
1: (79) r6 = *(u64 *)(r2 +0)
; struct task_struct *task = ctx->task;
2: (79) r7 = *(u64 *)(r1 +8)
; if (task == (void *)0) {
3: (55) if r7 != 0x0 goto pc+11
...
; BPF_SEQ_PRINTF(seq, "%8d %8d\n", task->tgid, task->pid);
26: (61) r1 = *(u32 *)(r7 +1372)
Type '(anon)' is not a struct
Basically, verifier will return btf_id 0 for task_struct.
Later on, when the code tries to access task->tgid, the
verifier correctly complains the type is '(anon)' and it is
not a struct. Users still need to backtrace to find out
what is going on.
Let us catch the invalid btf_id 0 earlier
and provide better message indicating btf_id is wrong.
The new error message looks like below:
R1 type=ctx expected=fp
; struct seq_file *seq = ctx->meta->seq;
0: (79) r2 = *(u64 *)(r1 +0)
func 'bpf_iter_task' arg0 has btf_id 29739 type STRUCT 'bpf_iter_meta'
; struct seq_file *seq = ctx->meta->seq;
1: (79) r6 = *(u64 *)(r2 +0)
; struct task_struct *task = ctx->task;
2: (79) r7 = *(u64 *)(r1 +8)
invalid btf_id for context argument offset 8
invalid bpf_context access off=8 size=8
[1] https://lore.kernel.org/bpf/20210727132532.2473636-1-hengqi.chen@gmail.com/
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210728183025.1461750-1-yhs@fb.com
Restrict bpf timers to array, hash (both preallocated and kmalloced), and
lru map types. The per-cpu maps with timers don't make sense, since 'struct
bpf_timer' is a part of map value. bpf timers in per-cpu maps would mean that
the number of timers depends on number of possible cpus and timers would not be
accessible from all cpus. lpm map support can be added in the future.
The timers in inner maps are supported.
The bpf_map_update/delete_elem() helpers and sys_bpf commands cancel and free
bpf_timer in a given map element.
Similar to 'struct bpf_spin_lock' BTF is required and it is used to validate
that map element indeed contains 'struct bpf_timer'.
Make check_and_init_map_value() init both bpf_spin_lock and bpf_timer when
map element data is reused in preallocated htab and lru maps.
Teach copy_map_value() to support both bpf_spin_lock and bpf_timer in a single
map element. There could be one of each, but not more than one. Due to 'one
bpf_timer in one element' restriction do not support timers in global data,
since global data is a map of single element, but from bpf program side it's
seen as many global variables and restriction of single global timer would be
odd. The sys_bpf map_freeze and sys_mmap syscalls are not allowed on maps with
timers, since user space could have corrupted mmap element and crashed the
kernel. The maps with timers cannot be readonly. Due to these restrictions
search for bpf_timer in datasec BTF in case it was placed in the global data to
report clear error.
The previous patch allowed 'struct bpf_timer' as a first field in a map
element only. Relax this restriction.
Refactor lru map to s/bpf_lru_push_free/htab_lru_push_free/ to cancel and free
the timer when lru map deletes an element as a part of it eviction algorithm.
Make sure that bpf program cannot access 'struct bpf_timer' via direct load/store.
The timer operation are done through helpers only.
This is similar to 'struct bpf_spin_lock'.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-5-alexei.starovoitov@gmail.com
Daniel Borkmann says:
====================
pull-request: bpf-next 2021-06-17
The following pull-request contains BPF updates for your *net-next* tree.
We've added 50 non-merge commits during the last 25 day(s) which contain
a total of 148 files changed, 4779 insertions(+), 1248 deletions(-).
The main changes are:
1) BPF infrastructure to migrate TCP child sockets from a listener to another
in the same reuseport group/map, from Kuniyuki Iwashima.
2) Add a provably sound, faster and more precise algorithm for tnum_mul() as
noted in https://arxiv.org/abs/2105.05398, from Harishankar Vishwanathan.
3) Streamline error reporting changes in libbpf as planned out in the
'libbpf: the road to v1.0' effort, from Andrii Nakryiko.
4) Add broadcast support to xdp_redirect_map(), from Hangbin Liu.
5) Extends bpf_map_lookup_and_delete_elem() functionality to 4 more map
types, that is, {LRU_,PERCPU_,LRU_PERCPU_,}HASH, from Denis Salopek.
6) Support new LLVM relocations in libbpf to make them more linker friendly,
also add a doc to describe the BPF backend relocations, from Yonghong Song.
7) Silence long standing KUBSAN complaints on register-based shifts in
interpreter, from Daniel Borkmann and Eric Biggers.
8) Add dummy PT_REGS macros in libbpf to fail BPF program compilation when
target arch cannot be determined, from Lorenz Bauer.
9) Extend AF_XDP to support large umems with 1M+ pages, from Magnus Karlsson.
10) Fix two minor libbpf tc BPF API issues, from Kumar Kartikeya Dwivedi.
11) Move libbpf BPF_SEQ_PRINTF/BPF_SNPRINTF macros that can be used by BPF
programs to bpf_helpers.h header, from Florent Revest.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Fix some spelling mistakes in comments:
aother ==> another
Netiher ==> Neither
desribe ==> describe
intializing ==> initializing
funciton ==> function
wont ==> won't and move the word 'the' at the end to the next line
accross ==> across
pathes ==> paths
triggerred ==> triggered
excute ==> execute
ether ==> either
conervative ==> conservative
convetion ==> convention
markes ==> marks
interpeter ==> interpreter
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210525025659.8898-2-thunder.leizhen@huawei.com
Add new helper:
long bpf_btf_find_by_name_kind(char *name, int name_sz, u32 kind, int flags)
Description
Find BTF type with given name and kind in vmlinux BTF or in module's BTFs.
Return
Returns btf_id and btf_obj_fd in lower and upper 32 bits.
It will be used by loader program to find btf_id to attach the program to
and to find btf_ids of ksyms.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-10-alexei.starovoitov@gmail.com
Similar to prog_load make btf_load command to be availble to
bpf_prog_type_syscall program.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-7-alexei.starovoitov@gmail.com
We can't currently allow to attach functions with variable arguments.
The problem is that we should save all the registers for arguments,
which is probably doable, but if caller uses more than 6 arguments,
we need stack data, which will be wrong, because of the extra stack
frame we do in bpf trampoline, so we could crash.
Also currently there's malformed trampoline code generated for such
functions at the moment as described in:
https://lore.kernel.org/bpf/20210429212834.82621-1-jolsa@kernel.org/
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210505132529.401047-1-jolsa@kernel.org
The variable id is being assigned a value that is never read, the
assignment is redundant and can be removed.
Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210326194348.623782-1-colin.king@canonical.com
This patch adds support to BPF verifier to allow bpf program calling
kernel function directly.
The use case included in this set is to allow bpf-tcp-cc to directly
call some tcp-cc helper functions (e.g. "tcp_cong_avoid_ai()"). Those
functions have already been used by some kernel tcp-cc implementations.
This set will also allow the bpf-tcp-cc program to directly call the
kernel tcp-cc implementation, For example, a bpf_dctcp may only want to
implement its own dctcp_cwnd_event() and reuse other dctcp_*() directly
from the kernel tcp_dctcp.c instead of reimplementing (or
copy-and-pasting) them.
The tcp-cc kernel functions mentioned above will be white listed
for the struct_ops bpf-tcp-cc programs to use in a later patch.
The white listed functions are not bounded to a fixed ABI contract.
Those functions have already been used by the existing kernel tcp-cc.
If any of them has changed, both in-tree and out-of-tree kernel tcp-cc
implementations have to be changed. The same goes for the struct_ops
bpf-tcp-cc programs which have to be adjusted accordingly.
This patch is to make the required changes in the bpf verifier.
First change is in btf.c, it adds a case in "btf_check_func_arg_match()".
When the passed in "btf->kernel_btf == true", it means matching the
verifier regs' states with a kernel function. This will handle the
PTR_TO_BTF_ID reg. It also maps PTR_TO_SOCK_COMMON, PTR_TO_SOCKET,
and PTR_TO_TCP_SOCK to its kernel's btf_id.
In the later libbpf patch, the insn calling a kernel function will
look like:
insn->code == (BPF_JMP | BPF_CALL)
insn->src_reg == BPF_PSEUDO_KFUNC_CALL /* <- new in this patch */
insn->imm == func_btf_id /* btf_id of the running kernel */
[ For the future calling function-in-kernel-module support, an array
of module btf_fds can be passed at the load time and insn->off
can be used to index into this array. ]
At the early stage of verifier, the verifier will collect all kernel
function calls into "struct bpf_kfunc_desc". Those
descriptors are stored in "prog->aux->kfunc_tab" and will
be available to the JIT. Since this "add" operation is similar
to the current "add_subprog()" and looking for the same insn->code,
they are done together in the new "add_subprog_and_kfunc()".
In the "do_check()" stage, the new "check_kfunc_call()" is added
to verify the kernel function call instruction:
1. Ensure the kernel function can be used by a particular BPF_PROG_TYPE.
A new bpf_verifier_ops "check_kfunc_call" is added to do that.
The bpf-tcp-cc struct_ops program will implement this function in
a later patch.
2. Call "btf_check_kfunc_args_match()" to ensure the regs can be
used as the args of a kernel function.
3. Mark the regs' type, subreg_def, and zext_dst.
At the later do_misc_fixups() stage, the new fixup_kfunc_call()
will replace the insn->imm with the function address (relative
to __bpf_call_base). If needed, the jit can find the btf_func_model
by calling the new bpf_jit_find_kfunc_model(prog, insn).
With the imm set to the function address, "bpftool prog dump xlated"
will be able to display the kernel function calls the same way as
it displays other bpf helper calls.
gpl_compatible program is required to call kernel function.
This feature currently requires JIT.
The verifier selftests are adjusted because of the changes in
the verbose log in add_subprog_and_kfunc().
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210325015142.1544736-1-kafai@fb.com
This patch moved the subprog specific logic from
btf_check_func_arg_match() to the new btf_check_subprog_arg_match().
The core logic is left in btf_check_func_arg_match() which
will be reused later to check the kernel function call.
The "if (!btf_type_is_ptr(t))" is checked first to improve the
indentation which will be useful for a later patch.
Some of the "btf_kind_str[]" usages is replaced with the shortcut
"btf_type_str(t)".
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210325015136.1544504-1-kafai@fb.com
Alexei Starovoitov says:
====================
pull-request: bpf-next 2021-03-09
The following pull-request contains BPF updates for your *net-next* tree.
We've added 90 non-merge commits during the last 17 day(s) which contain
a total of 114 files changed, 5158 insertions(+), 1288 deletions(-).
The main changes are:
1) Faster bpf_redirect_map(), from Björn.
2) skmsg cleanup, from Cong.
3) Support for floating point types in BTF, from Ilya.
4) Documentation for sys_bpf commands, from Joe.
5) Support for sk_lookup in bpf_prog_test_run, form Lorenz.
6) Enable task local storage for tracing programs, from Song.
7) bpf_for_each_map_elem() helper, from Yonghong.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
On the kernel side, introduce a new btf_kind_operations. It is
similar to that of BTF_KIND_INT, however, it does not need to
handle encodings and bit offsets. Do not implement printing, since
the kernel does not know how to format floating-point values.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210226202256.116518-7-iii@linux.ibm.com
Instead of using integer literal here and there use macro name for
better context.
Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210225202629.585485-1-me@ubique.spb.ru
Now it is possible for global function to have a pointer argument that
points to something different than struct. Drop the irrelevant log
message and keep the logic same.
Fixes: e5069b9c23 ("bpf: Support pointers in global func args")
Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210223090416.333943-1-me@ubique.spb.ru
Add an ability to pass a pointer to a type with known size in arguments
of a global function. Such pointers may be used to overcome the limit on
the maximum number of arguments, avoid expensive and tricky workarounds
and to have multiple output arguments.
A referenced type may contain pointers but indirect access through them
isn't supported.
The implementation consists of two parts. If a global function has an
argument that is a pointer to a type with known size then:
1) In btf_check_func_arg_match(): check that the corresponding
register points to NULL or to a valid memory region that is large enough
to contain the expected argument's type.
2) In btf_prepare_func_args(): set the corresponding register type to
PTR_TO_MEM_OR_NULL and its size to the size of the expected type.
Only global functions are supported because allowance of pointers for
static functions might break validation. Consider the following
scenario. A static function has a pointer argument. A caller passes
pointer to its stack memory. Because the callee can change referenced
memory verifier cannot longer assume any particular slot type of the
caller's stack memory hence the slot type is changed to SLOT_MISC. If
there is an operation that relies on slot type other than SLOT_MISC then
verifier won't be able to infer safety of the operation.
When verifier sees a static function that has a pointer argument
different from PTR_TO_CTX then it skips arguments check and continues
with "inline" validation with more information available. The operation
that relies on the particular slot type now succeeds.
Because global functions were not allowed to have pointer arguments
different from PTR_TO_CTX it's not possible to break existing and valid
code.
Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210212205642.620788-4-me@ubique.spb.ru
Using "reg" for an array of bpf_reg_state and "reg[i + 1]" for an
individual bpf_reg_state is error-prone and verbose. Use "regs" for the
former and "reg" for the latter as other code nearby does.
Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210212205642.620788-2-me@ubique.spb.ru
llvm patch https://reviews.llvm.org/D84002 permitted
to emit empty rodata datasec if the elf .rodata section
contains read-only data from local variables. These
local variables will be not emitted as BTF_KIND_VARs
since llvm converted these local variables as
static variables with private linkage without debuginfo
types. Such an empty rodata datasec will make
skeleton code generation easy since for skeleton
a rodata struct will be generated if there is a
.rodata elf section. The existence of a rodata
btf datasec is also consistent with the existence
of a rodata map created by libbpf.
The btf with such an empty rodata datasec will fail
in the kernel though as kernel will reject a datasec
with zero vlen and zero size. For example, for the below code,
int sys_enter(void *ctx)
{
int fmt[6] = {1, 2, 3, 4, 5, 6};
int dst[6];
bpf_probe_read(dst, sizeof(dst), fmt);
return 0;
}
We got the below btf (bpftool btf dump ./test.o):
[1] PTR '(anon)' type_id=0
[2] FUNC_PROTO '(anon)' ret_type_id=3 vlen=1
'ctx' type_id=1
[3] INT 'int' size=4 bits_offset=0 nr_bits=32 encoding=SIGNED
[4] FUNC 'sys_enter' type_id=2 linkage=global
[5] INT 'char' size=1 bits_offset=0 nr_bits=8 encoding=SIGNED
[6] ARRAY '(anon)' type_id=5 index_type_id=7 nr_elems=4
[7] INT '__ARRAY_SIZE_TYPE__' size=4 bits_offset=0 nr_bits=32 encoding=(none)
[8] VAR '_license' type_id=6, linkage=global-alloc
[9] DATASEC '.rodata' size=0 vlen=0
[10] DATASEC 'license' size=0 vlen=1
type_id=8 offset=0 size=4
When loading the ./test.o to the kernel with bpftool,
we see the following error:
libbpf: Error loading BTF: Invalid argument(22)
libbpf: magic: 0xeb9f
...
[6] ARRAY (anon) type_id=5 index_type_id=7 nr_elems=4
[7] INT __ARRAY_SIZE_TYPE__ size=4 bits_offset=0 nr_bits=32 encoding=(none)
[8] VAR _license type_id=6 linkage=1
[9] DATASEC .rodata size=24 vlen=0 vlen == 0
libbpf: Error loading .BTF into kernel: -22. BTF is optional, ignoring.
Basically, libbpf changed .rodata datasec size to 24 since elf .rodata
section size is 24. The kernel then rejected the BTF since vlen = 0.
Note that the above kernel verifier failure can be worked around with
changing local variable "fmt" to a static or global, optionally const, variable.
This patch permits a datasec with vlen = 0 in kernel.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210119153519.3901963-1-yhs@fb.com
Conflicts:
drivers/net/can/dev.c
commit 03f16c5075 ("can: dev: can_restart: fix use after free bug")
commit 3e77f70e73 ("can: dev: move driver related infrastructure into separate subdir")
Code move.
drivers/net/dsa/b53/b53_common.c
commit 8e4052c32d ("net: dsa: b53: fix an off by one in checking "vlan->vid"")
commit b7a9e0da2d ("net: switchdev: remove vid_begin -> vid_end range from VLAN objects")
Field rename.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Add support for directly accessing kernel module variables from BPF programs
using special ldimm64 instructions. This functionality builds upon vmlinux
ksym support, but extends ldimm64 with src_reg=BPF_PSEUDO_BTF_ID to allow
specifying kernel module BTF's FD in insn[1].imm field.
During BPF program load time, verifier will resolve FD to BTF object and will
take reference on BTF object itself and, for module BTFs, corresponding module
as well, to make sure it won't be unloaded from under running BPF program. The
mechanism used is similar to how bpf_prog keeps track of used bpf_maps.
One interesting change is also in how per-CPU variable is determined. The
logic is to find .data..percpu data section in provided BTF, but both vmlinux
and module each have their own .data..percpu entries in BTF. So for module's
case, the search for DATASEC record needs to look at only module's added BTF
types. This is implemented with custom search function.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/bpf/20210112075520.4103414-6-andrii@kernel.org
Some modules don't declare any new types and end up with an empty BTF,
containing only valid BTF header and no types or strings sections. This
currently causes BTF validation error. There is nothing wrong with such BTF,
so fix the issue by allowing module BTFs with no types or strings.
Fixes: 36e68442d1 ("bpf: Load and verify kernel module BTFs")
Reported-by: Christopher William Snowhill <chris@kode54.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210110070341.1380086-1-andrii@kernel.org
Add ability for user-space programs to specify non-vmlinux BTF when attaching
BTF-powered BPF programs: raw_tp, fentry/fexit/fmod_ret, LSM, etc. For this,
attach_prog_fd (now with the alias name attach_btf_obj_fd) should specify FD
of a module or vmlinux BTF object. For backwards compatibility reasons,
0 denotes vmlinux BTF. Only kernel BTF (vmlinux or module) can be specified.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201203204634.1325171-11-andrii@kernel.org
Remove a permeating assumption thoughout BPF verifier of vmlinux BTF. Instead,
wherever BTF type IDs are involved, also track the instance of struct btf that
goes along with the type ID. This allows to gradually add support for kernel
module BTFs and using/tracking module types across BPF helper calls and
registers.
This patch also renames btf_id() function to btf_obj_id() to minimize naming
clash with using btf_id to denote BTF *type* ID, rather than BTF *object*'s ID.
Also, altough btf_vmlinux can't get destructed and thus doesn't need
refcounting, module BTFs need that, so apply BTF refcounting universally when
BPF program is using BTF-powered attachment (tp_btf, fentry/fexit, etc). This
makes for simpler clean up code.
Now that BTF type ID is not enough to uniquely identify a BTF type, extend BPF
trampoline key to include BTF object ID. To differentiate that from target
program BPF ID, set 31st bit of type ID. BTF type IDs (at least currently) are
not allowed to take full 32 bits, so there is no danger of confusing that bit
with a valid BTF type ID.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201203204634.1325171-10-andrii@kernel.org
Make sure btf_parse_module() is compiled out if module BTFs are not enabled.
Fixes: 36e68442d1 ("bpf: Load and verify kernel module BTFs")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201111040645.903494-1-andrii@kernel.org
Add kernel module listener that will load/validate and unload module BTF.
Module BTFs gets ID generated for them, which makes it possible to iterate
them with existing BTF iteration API. They are given their respective module's
names, which will get reported through GET_OBJ_INFO API. They are also marked
as in-kernel BTFs for tooling to distinguish them from user-provided BTFs.
Also, similarly to vmlinux BTF, kernel module BTFs are exposed through
sysfs as /sys/kernel/btf/<module-name>. This is convenient for user-space
tools to inspect module BTF contents and dump their types with existing tools:
[vmuser@archvm bpf]$ ls -la /sys/kernel/btf
total 0
drwxr-xr-x 2 root root 0 Nov 4 19:46 .
drwxr-xr-x 13 root root 0 Nov 4 19:46 ..
...
-r--r--r-- 1 root root 888 Nov 4 19:46 irqbypass
-r--r--r-- 1 root root 100225 Nov 4 19:46 kvm
-r--r--r-- 1 root root 35401 Nov 4 19:46 kvm_intel
-r--r--r-- 1 root root 120 Nov 4 19:46 pcspkr
-r--r--r-- 1 root root 399 Nov 4 19:46 serio_raw
-r--r--r-- 1 root root 4094095 Nov 4 19:46 vmlinux
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/bpf/20201110011932.3201430-5-andrii@kernel.org
Allocate ID for vmlinux BTF. This makes it visible when iterating over all BTF
objects in the system. To allow distinguishing vmlinux BTF (and later kernel
module BTF) from user-provided BTFs, expose extra kernel_btf flag, as well as
BTF name ("vmlinux" for vmlinux BTF, will equal to module's name for module
BTF). We might want to later allow specifying BTF name for user-provided BTFs
as well, if that makes sense. But currently this is reserved only for
in-kernel BTFs.
Having in-kernel BTFs exposed IDs will allow to extend BPF APIs that require
in-kernel BTF type with ability to specify BTF types from kernel modules, not
just vmlinux BTF. This will be implemented in a follow up patch set for
fentry/fexit/fmod_ret/lsm/etc.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20201110011932.3201430-3-andrii@kernel.org
Adjust in-kernel BTF implementation to support a split BTF mode of operation.
Changes are mostly mirroring libbpf split BTF changes, with the exception of
start_id being 0 for in-kernel implementation due to simpler read-only mode.
Otherwise, for split BTF logic, most of the logic of jumping to base BTF,
where necessary, is encapsulated in few helper functions. Type numbering and
string offset in a split BTF are logically continuing where base BTF ends, so
most of the high-level logic is kept without changes.
Type verification and size resolution is only doing an added resolution of new
split BTF types and relies on already cached size and type resolution results
in the base BTF.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20201110011932.3201430-2-andrii@kernel.org
Add bpf_per_cpu_ptr() to help bpf programs access percpu vars.
bpf_per_cpu_ptr() has the same semantic as per_cpu_ptr() in the kernel
except that it may return NULL. This happens when the cpu parameter is
out of range. So the caller must check the returned value.
Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200929235049.2533242-5-haoluo@google.com
Pseudo_btf_id is a type of ld_imm insn that associates a btf_id to a
ksym so that further dereferences on the ksym can use the BTF info
to validate accesses. Internally, when seeing a pseudo_btf_id ld insn,
the verifier reads the btf_id stored in the insn[0]'s imm field and
marks the dst_reg as PTR_TO_BTF_ID. The btf_id points to a VAR_KIND,
which is encoded in btf_vminux by pahole. If the VAR is not of a struct
type, the dst reg will be marked as PTR_TO_MEM instead of PTR_TO_BTF_ID
and the mem_size is resolved to the size of the VAR's type.
>From the VAR btf_id, the verifier can also read the address of the
ksym's corresponding kernel var from kallsyms and use that to fill
dst_reg.
Therefore, the proper functionality of pseudo_btf_id depends on (1)
kallsyms and (2) the encoding of kernel global VARs in pahole, which
should be available since pahole v1.18.
Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200929235049.2533242-2-haoluo@google.com
Eelco reported we can't properly access arguments if the tracing
program is attached to extension program.
Having following program:
SEC("classifier/test_pkt_md_access")
int test_pkt_md_access(struct __sk_buff *skb)
with its extension:
SEC("freplace/test_pkt_md_access")
int test_pkt_md_access_new(struct __sk_buff *skb)
and tracing that extension with:
SEC("fentry/test_pkt_md_access_new")
int BPF_PROG(fentry, struct sk_buff *skb)
It's not possible to access skb argument in the fentry program,
with following error from verifier:
; int BPF_PROG(fentry, struct sk_buff *skb)
0: (79) r1 = *(u64 *)(r1 +0)
invalid bpf_context access off=0 size=8
The problem is that btf_ctx_access gets the context type for the
traced program, which is in this case the extension.
But when we trace extension program, we want to get the context
type of the program that the extension is attached to, so we can
access the argument properly in the trace program.
This version of the patch is tweaked slightly from Jiri's original one,
since the refactoring in the previous patches means we have to get the
target prog type from the new variable in prog->aux instead of directly
from the target prog.
Reported-by: Eelco Chaudron <echaudro@redhat.com>
Suggested-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/160138355278.48470.17057040257274725638.stgit@toke.dk
In preparation for allowing multiple attachments of freplace programs, move
the references to the target program and trampoline into the
bpf_tracing_link structure when that is created. To do this atomically,
introduce a new mutex in prog->aux to protect writing to the two pointers
to target prog and trampoline, and rename the members to make it clear that
they are related.
With this change, it is no longer possible to attach the same tracing
program multiple times (detaching in-between), since the reference from the
tracing program to the target disappears on the first attach. However,
since the next patch will let the caller supply an attach target, that will
also make it possible to attach to the same place multiple times.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/160138355059.48470.2503076992210324984.stgit@toke.dk
A helper is added to allow seq file writing of kernel data
structures using vmlinux BTF. Its signature is
long bpf_seq_printf_btf(struct seq_file *m, struct btf_ptr *ptr,
u32 btf_ptr_size, u64 flags);
Flags and struct btf_ptr definitions/use are identical to the
bpf_snprintf_btf helper, and the helper returns 0 on success
or a negative error value.
Suggested-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1601292670-1616-8-git-send-email-alan.maguire@oracle.com
generalize the "seq_show" seq file support in btf.c to support
a generic show callback of which we support two instances; the
current seq file show, and a show with snprintf() behaviour which
instead writes the type data to a supplied string.
Both classes of show function call btf_type_show() with different
targets; the seq file or the string to be written. In the string
case we need to track additional data - length left in string to write
and length to return that we would have written (a la snprintf).
By default show will display type information, field members and
their types and values etc, and the information is indented
based upon structure depth. Zeroed fields are omitted.
Show however supports flags which modify its behaviour:
BTF_SHOW_COMPACT - suppress newline/indent.
BTF_SHOW_NONAME - suppress show of type and member names.
BTF_SHOW_PTR_RAW - do not obfuscate pointer values.
BTF_SHOW_UNSAFE - do not copy data to safe buffer before display.
BTF_SHOW_ZERO - show zeroed values (by default they are not shown).
Signed-off-by: Alan Maguire <alan.maguire@oracle.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1601292670-1616-3-git-send-email-alan.maguire@oracle.com
In preparation for moving code around, change a bunch of references to
env->log (and the verbose() logging helper) to use bpf_log() and a direct
pointer to struct bpf_verifier_log. While we're touching the function
signature, mark the 'prog' argument to bpf_check_type_match() as const.
Also enhance the bpf_verifier_log_needed() check to handle NULL pointers
for the log struct so we can re-use the code with logging disabled.
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Function prototypes using ARG_PTR_TO_BTF_ID currently use two ways to signal
which BTF IDs are acceptable. First, bpf_func_proto.btf_id is an array of
IDs, one for each argument. This array is only accessed up to the highest
numbered argument that uses ARG_PTR_TO_BTF_ID and may therefore be less than
five arguments long. It usually points at a BTF_ID_LIST. Second, check_btf_id
is a function pointer that is called by the verifier if present. It gets the
actual BTF ID of the register, and the argument number we're currently checking.
It turns out that the only user check_arg_btf_id ignores the argument, and is
simply used to check whether the BTF ID has a struct sock_common at it's start.
Replace both of these mechanisms with an explicit BTF ID for each argument
in a function proto. Thanks to btf_struct_ids_match this is very flexible:
check_arg_btf_id can be replaced by requiring struct sock_common.
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200921121227.255763-5-lmb@cloudflare.com
bsearch doesn't modify the contents of the array, so we can take a const pointer.
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200921121227.255763-2-lmb@cloudflare.com
Adding support to define sorted set of BTF ID values.
Following defines sorted set of BTF ID values:
BTF_SET_START(btf_allowlist_d_path)
BTF_ID(func, vfs_truncate)
BTF_ID(func, vfs_fallocate)
BTF_ID(func, dentry_open)
BTF_ID(func, vfs_getattr)
BTF_ID(func, filp_close)
BTF_SET_END(btf_allowlist_d_path)
It defines following 'struct btf_id_set' variable to access
values and count:
struct btf_id_set btf_allowlist_d_path;
Adding 'allowed' callback to struct bpf_func_proto, to allow
verifier the check on allowed callers.
Adding btf_id_set_contains function, which will be used by
allowed callbacks to verify the caller's BTF ID value is
within allowed set.
Also removing extra '\' in __BTF_ID_LIST macro.
Added BTF_SET_START_GLOBAL macro for global sets.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200825192124.710397-10-jolsa@kernel.org
Adding btf_struct_ids_match function to check if given address provided
by BTF object + offset is also address of another nested BTF object.
This allows to pass an argument to helper, which is defined via parent
BTF object + offset, like for bpf_d_path (added in following changes):
SEC("fentry/filp_close")
int BPF_PROG(prog_close, struct file *file, void *id)
{
...
ret = bpf_d_path(&file->f_path, ...
The first bpf_d_path argument is hold by verifier as BTF file object
plus offset of f_path member.
The btf_struct_ids_match function will walk the struct file object and
check if there's nested struct path object on the given offset.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200825192124.710397-9-jolsa@kernel.org
Adding btf_struct_walk function that walks through the
struct type + given offset and returns following values:
enum bpf_struct_walk_result {
/* < 0 error */
WALK_SCALAR = 0,
WALK_PTR,
WALK_STRUCT,
};
WALK_SCALAR - when SCALAR_VALUE is found
WALK_PTR - when pointer value is found, its ID is stored
in 'next_btf_id' output param
WALK_STRUCT - when nested struct object is found, its ID is stored
in 'next_btf_id' output param
It will be used in following patches to get all nested
struct objects for given type and offset.
The btf_struct_access now calls btf_struct_walk function,
as long as it gets nested structs as return value.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200825192124.710397-8-jolsa@kernel.org
Andrii suggested we can simply jump to again label
instead of making recursion call.
Suggested-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200825192124.710397-7-jolsa@kernel.org
Adding type_id pointer as argument to __btf_resolve_size
to return also BTF ID of the resolved type. It will be
used in following changes.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200825192124.710397-6-jolsa@kernel.org
If the resolved type is array, make btf_resolve_size return also
ID of the elem type. It will be needed in following changes.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200825192124.710397-5-jolsa@kernel.org
Moving btf_resolve_size into __btf_resolve_size and
keeping btf_resolve_size public with just first 3
arguments, because the rest of the arguments are not
used by outside callers.
Following changes are adding more arguments, which
are not useful to outside callers. They will be added
to the __btf_resolve_size function.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200825192124.710397-4-jolsa@kernel.org
Daniel Borkmann says:
====================
pull-request: bpf-next 2020-08-04
The following pull-request contains BPF updates for your *net-next* tree.
We've added 73 non-merge commits during the last 9 day(s) which contain
a total of 135 files changed, 4603 insertions(+), 1013 deletions(-).
The main changes are:
1) Implement bpf_link support for XDP. Also add LINK_DETACH operation for the BPF
syscall allowing processes with BPF link FD to force-detach, from Andrii Nakryiko.
2) Add BPF iterator for map elements and to iterate all BPF programs for efficient
in-kernel inspection, from Yonghong Song and Alexei Starovoitov.
3) Separate bpf_get_{stack,stackid}() helpers for perf events in BPF to avoid
unwinder errors, from Song Liu.
4) Allow cgroup local storage map to be shared between programs on the same
cgroup. Also extend BPF selftests with coverage, from YiFei Zhu.
5) Add BPF exception tables to ARM64 JIT in order to be able to JIT BPF_PROBE_MEM
load instructions, from Jean-Philippe Brucker.
6) Follow-up fixes on BPF socket lookup in combination with reuseport group
handling. Also add related BPF selftests, from Jakub Sitnicki.
7) Allow to use socket storage in BPF_PROG_TYPE_CGROUP_SOCK-typed programs for
socket create/release as well as bind functions, from Stanislav Fomichev.
8) Fix an info leak in xsk_getsockopt() when retrieving XDP stats via old struct
xdp_statistics, from Peilin Ye.
9) Fix PT_REGS_RC{,_CORE}() macros in libbpf for MIPS arch, from Jerry Crunchtime.
10) Extend BPF kernel test infra with skb->family and skb->{local,remote}_ip{4,6}
fields and allow user space to specify skb->dev via ifindex, from Dmitry Yakunin.
11) Fix a bpftool segfault due to missing program type name and make it more robust
to prevent them in future gaps, from Quentin Monnet.
12) Consolidate cgroup helper functions across selftests and fix a v6 localhost
resolver issue, from John Fastabend.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
Readonly and readwrite buffer register states
are introduced. Totally four states,
PTR_TO_RDONLY_BUF[_OR_NULL] and PTR_TO_RDWR_BUF[_OR_NULL]
are supported. As suggested by their respective
names, PTR_TO_RDONLY_BUF[_OR_NULL] are for
readonly buffers and PTR_TO_RDWR_BUF[_OR_NULL]
for read/write buffers.
These new register states will be used
by later bpf map element iterator.
New register states share some similarity to
PTR_TO_TP_BUFFER as it will calculate accessed buffer
size during verification time. The accessed buffer
size will be later compared to other metrics during
later attach/link_create time.
Similar to reg_state PTR_TO_BTF_ID_OR_NULL in bpf
iterator programs, PTR_TO_RDONLY_BUF_OR_NULL or
PTR_TO_RDWR_BUF_OR_NULL reg_types can be set at
prog->aux->bpf_ctx_arg_aux, and bpf verifier will
retrieve the values during btf_ctx_access().
Later bpf map element iterator implementation
will show how such information will be assigned
during target registeration time.
The verifier is also enhanced such that PTR_TO_RDONLY_BUF
can be passed to ARG_PTR_TO_MEM[_OR_NULL] helper argument, and
PTR_TO_RDWR_BUF can be passed to ARG_PTR_TO_MEM[_OR_NULL] or
ARG_PTR_TO_UNINIT_MEM.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200723184111.590274-1-yhs@fb.com
One additional field btf_id is added to struct
bpf_ctx_arg_aux to store the precomputed btf_ids.
The btf_id is computed at build time with
BTF_ID_LIST or BTF_ID_LIST_GLOBAL macro definitions.
All existing bpf iterators are changed to used
pre-compute btf_ids.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200720163403.1393551-1-yhs@fb.com
Currently, socket types (struct tcp_sock, udp_sock, etc.)
used by bpf_skc_to_*() helpers are computed when vmlinux_btf
is first built in the kernel.
Commit 5a2798ab32
("bpf: Add BTF_ID_LIST/BTF_ID/BTF_ID_UNUSED macros")
implemented a mechanism to compute btf_ids at kernel build
time which can simplify kernel implementation and reduce
runtime overhead by removing in-kernel btf_id calculation.
This patch did exactly this, removing in-kernel btf_id
computation and utilizing build-time btf_id computation.
If CONFIG_DEBUG_INFO_BTF is not defined, BTF_ID_LIST will
define an array with size of 5, which is not enough for
btf_sock_ids. So define its own static array if
CONFIG_DEBUG_INFO_BTF is not defined.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200720163358.1393023-1-yhs@fb.com
Alexei Starovoitov says:
====================
pull-request: bpf-next 2020-07-13
The following pull-request contains BPF updates for your *net-next* tree.
We've added 36 non-merge commits during the last 7 day(s) which contain
a total of 62 files changed, 2242 insertions(+), 468 deletions(-).
The main changes are:
1) Avoid trace_printk warning banner by switching bpf_trace_printk to use
its own tracing event, from Alan.
2) Better libbpf support on older kernels, from Andrii.
3) Additional AF_XDP stats, from Ciara.
4) build time resolution of BTF IDs, from Jiri.
5) BPF_CGROUP_INET_SOCK_RELEASE hook, from Stanislav.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
This way the ID is resolved during compile time,
and we can remove the runtime name search.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200711215329.41165-7-jolsa@kernel.org
Now when we moved the helpers btf_id arrays into .BTF_ids section,
we can remove the code that resolve those IDs in runtime.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200711215329.41165-6-jolsa@kernel.org
To ensure btf_ctx_access() is safe the verifier checks that the BTF
arg type is an int, enum, or pointer. When the function does the
BTF arg lookup it uses the calculation 'arg = off / 8' using the
fact that registers are 8B. This requires that the first arg is
in the first reg, the second in the second, and so on. However,
for __int128 the arg will consume two registers by default LLVM
implementation. So this will cause the arg layout assumed by the
'arg = off / 8' calculation to be incorrect.
Because __int128 is uncommon this patch applies the easiest fix and
will force int types to be sizeof(u64) or smaller so that they will
fit in a single register.
v2: remove unneeded parens per Andrii's feedback
Fixes: 9e15db6613 ("bpf: Implement accurate raw_tp context access via BTF")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/159303723962.11287.13309537171132420717.stgit@john-Precision-5820-Tower
The helper is used in tracing programs to cast a socket
pointer to a tcp6_sock pointer.
The return value could be NULL if the casting is illegal.
A new helper return type RET_PTR_TO_BTF_ID_OR_NULL is added
so the verifier is able to deduce proper return types for the helper.
Different from the previous BTF_ID based helpers,
the bpf_skc_to_tcp6_sock() argument can be several possible
btf_ids. More specifically, all possible socket data structures
with sock_common appearing in the first in the memory layout.
This patch only added socket types related to tcp and udp.
All possible argument btf_id and return value btf_id
for helper bpf_skc_to_tcp6_sock() are pre-calculcated and
cached. In the future, it is even possible to precompute
these btf_id's at kernel build time.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200623230809.3988195-1-yhs@fb.com
There are multiple use-cases when it's convenient to have access to bpf
map fields, both `struct bpf_map` and map type specific struct-s such as
`struct bpf_array`, `struct bpf_htab`, etc.
For example while working with sock arrays it can be necessary to
calculate the key based on map->max_entries (some_hash % max_entries).
Currently this is solved by communicating max_entries via "out-of-band"
channel, e.g. via additional map with known key to get info about target
map. That works, but is not very convenient and error-prone while
working with many maps.
In other cases necessary data is dynamic (i.e. unknown at loading time)
and it's impossible to get it at all. For example while working with a
hash table it can be convenient to know how much capacity is already
used (bpf_htab.count.counter for BPF_F_NO_PREALLOC case).
At the same time kernel knows this info and can provide it to bpf
program.
Fill this gap by adding support to access bpf map fields from bpf
program for both `struct bpf_map` and map type specific fields.
Support is implemented via btf_struct_access() so that a user can define
their own `struct bpf_map` or map type specific struct in their program
with only necessary fields and preserve_access_index attribute, cast a
map to this struct and use a field.
For example:
struct bpf_map {
__u32 max_entries;
} __attribute__((preserve_access_index));
struct bpf_array {
struct bpf_map map;
__u32 elem_size;
} __attribute__((preserve_access_index));
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 4);
__type(key, __u32);
__type(value, __u32);
} m_array SEC(".maps");
SEC("cgroup_skb/egress")
int cg_skb(void *ctx)
{
struct bpf_array *array = (struct bpf_array *)&m_array;
struct bpf_map *map = (struct bpf_map *)&m_array;
/* .. use map->max_entries or array->map.max_entries .. */
}
Similarly to other btf_struct_access() use-cases (e.g. struct tcp_sock
in net/ipv4/bpf_tcp_ca.c) the patch allows access to any fields of
corresponding struct. Only reading from map fields is supported.
For btf_struct_access() to work there should be a way to know btf id of
a struct that corresponds to a map type. To get btf id there should be a
way to get a stringified name of map-specific struct, such as
"bpf_array", "bpf_htab", etc for a map type. Two new fields are added to
`struct bpf_map_ops` to handle it:
* .map_btf_name keeps a btf name of a struct returned by map_alloc();
* .map_btf_id is used to cache btf id of that struct.
To make btf ids calculation cheaper they're calculated once while
preparing btf_vmlinux and cached same way as it's done for btf_id field
of `struct bpf_func_proto`
While calculating btf ids, struct names are NOT checked for collision.
Collisions will be checked as a part of the work to prepare btf ids used
in verifier in compile time that should land soon. The only known
collision for `struct bpf_htab` (kernel/bpf/hashtab.c vs
net/core/sock_map.c) was fixed earlier.
Both new fields .map_btf_name and .map_btf_id must be set for a map type
for the feature to work. If neither is set for a map type, verifier will
return ENOTSUPP on a try to access map_ptr of corresponding type. If
just one of them set, it's verifier misconfiguration.
Only `struct bpf_array` for BPF_MAP_TYPE_ARRAY and `struct bpf_htab` for
BPF_MAP_TYPE_HASH are supported by this patch. Other map types will be
supported separately.
The feature is available only for CONFIG_DEBUG_INFO_BTF=y and gated by
perfmon_capable() so that unpriv programs won't have access to bpf map
fields.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/6479686a0cd1e9067993df57b4c3eef0e276fec9.1592600985.git.rdna@fb.com
btf_parse_vmlinux() implements manual search for struct bpf_ctx_convert
since at the time of implementing btf_find_by_name_kind() was not
available.
Later btf_find_by_name_kind() was introduced in 27ae7997a6 ("bpf:
Introduce BPF_PROG_TYPE_STRUCT_OPS"). It provides similar search
functionality and can be leveraged in btf_parse_vmlinux(). Do it.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/6e12d5c3e8a3d552925913ef73a695dd1bb27800.1592600985.git.rdna@fb.com
Commit b121b341e5 ("bpf: Add PTR_TO_BTF_ID_OR_NULL
support") adds a field btf_id_or_null_non0_off to
bpf_prog->aux structure to indicate that the
first ctx argument is PTR_TO_BTF_ID reg_type and
all others are PTR_TO_BTF_ID_OR_NULL.
This approach does not really scale if we have
other different reg types in the future, e.g.,
a pointer to a buffer.
This patch enables bpf_iter targets registering ctx argument
reg types which may be different from the default one.
For example, for pointers to structures, the default reg_type
is PTR_TO_BTF_ID for tracing program. The target can register
a particular pointer type as PTR_TO_BTF_ID_OR_NULL which can
be used by the verifier to enforce accesses.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200513180221.2949882-1-yhs@fb.com
Add bpf_reg_type PTR_TO_BTF_ID_OR_NULL support.
For tracing/iter program, the bpf program context
definition, e.g., for previous bpf_map target, looks like
struct bpf_iter__bpf_map {
struct bpf_iter_meta *meta;
struct bpf_map *map;
};
The kernel guarantees that meta is not NULL, but
map pointer maybe NULL. The NULL map indicates that all
objects have been traversed, so bpf program can take
proper action, e.g., do final aggregation and/or send
final report to user space.
Add btf_id_or_null_non0_off to prog->aux structure, to
indicate that if the context access offset is not 0,
set to PTR_TO_BTF_ID_OR_NULL instead of PTR_TO_BTF_ID.
This bit is set for tracing/iter program.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200509175912.2476576-1-yhs@fb.com
Add ability to fetch bpf_link details through BPF_OBJ_GET_INFO_BY_FD command.
Also enhance show_fdinfo to potentially include bpf_link type-specific
information (similarly to obj_info).
Also introduce enum bpf_link_type stored in bpf_link itself and expose it in
UAPI. bpf_link_tracing also now will store and return bpf_attach_type.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200429001614.1544-5-andriin@fb.com
The bounds checking for the arguments accessed in the BPF program breaks
when the expected_attach_type is not BPF_TRACE_FEXIT, BPF_LSM_MAC or
BPF_MODIFY_RETURN resulting in no check being done for the default case
(the programs which do not receive the return value of the attached
function in its arguments) when the index of the argument being accessed
is equal to the number of arguments (nr_args).
This was a result of a misplaced "else if" block introduced by the
Commit 6ba43b761c ("bpf: Attachment verification for
BPF_MODIFY_RETURN")
Fixes: 6ba43b761c ("bpf: Attachment verification for BPF_MODIFY_RETURN")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200330144246.338-1-kpsingh@chromium.org
JITed BPF programs are dynamically attached to the LSM hooks
using BPF trampolines. The trampoline prologue generates code to handle
conversion of the signature of the hook to the appropriate BPF context.
The allocated trampoline programs are attached to the nop functions
initialized as LSM hooks.
BPF_PROG_TYPE_LSM programs must have a GPL compatible license and
and need CAP_SYS_ADMIN (required for loading eBPF programs).
Upon attachment:
* A BPF fexit trampoline is used for LSM hooks with a void return type.
* A BPF fmod_ret trampoline is used for LSM hooks which return an
int. The attached programs can override the return value of the
bpf LSM hook to indicate a MAC Policy decision.
Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Reviewed-by: Florent Revest <revest@google.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Link: https://lore.kernel.org/bpf/20200329004356.27286-5-kpsingh@chromium.org
Overlapping header include additions in macsec.c
A bug fix in 'net' overlapping with the removal of 'version'
string in ena_netdev.c
Overlapping test additions in selftests Makefile
Overlapping PCI ID table adjustments in iwlwifi driver.
Signed-off-by: David S. Miller <davem@davemloft.net>
Trying to initialize a structure with "= {};" will not always clean out
all padding locations in a structure. So be explicit and call memset to
initialize everything for a number of bpf information structures that
are then copied from userspace, sometimes from smaller memory locations
than the size of the structure.
Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200320162258.GA794295@kroah.com
Simplify gen_btf logic to make it work with llvm-objcopy. The existing
'file format' and 'architecture' parsing logic is brittle and does not
work with llvm-objcopy/llvm-objdump.
'file format' output of llvm-objdump>=11 will match GNU objdump, but
'architecture' (bfdarch) may not.
.BTF in .tmp_vmlinux.btf is non-SHF_ALLOC. Add the SHF_ALLOC flag
because it is part of vmlinux image used for introspection. C code
can reference the section via linker script defined __start_BTF and
__stop_BTF. This fixes a small problem that previous .BTF had the
SHF_WRITE flag (objcopy -I binary -O elf* synthesized .data).
Additionally, `objcopy -I binary` synthesized symbols
_binary__btf_vmlinux_bin_start and _binary__btf_vmlinux_bin_stop (not
used elsewhere) are replaced with more commonplace __start_BTF and
__stop_BTF.
Add 2>/dev/null because GNU objcopy (but not llvm-objcopy) warns
"empty loadable segment detected at vaddr=0xffffffff81000000, is this intentional?"
We use a dd command to change the e_type field in the ELF header from
ET_EXEC to ET_REL so that lld will accept .btf.vmlinux.bin.o. Accepting
ET_EXEC as an input file is an extremely rare GNU ld feature that lld
does not intend to support, because this is error-prone.
The output section description .BTF in include/asm-generic/vmlinux.lds.h
avoids potential subtle orphan section placement issues and suppresses
--orphan-handling=warn warnings.
Fixes: df786c9b94 ("bpf: Force .BTF section start to zero when dumping from vmlinux")
Fixes: cb0cc635c7 ("powerpc: Include .BTF section")
Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Fangrui Song <maskray@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Stanislav Fomichev <sdf@google.com>
Tested-by: Andrii Nakryiko <andriin@fb.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Link: https://github.com/ClangBuiltLinux/linux/issues/871
Link: https://lore.kernel.org/bpf/20200318222746.173648-1-maskray@google.com
btf_enum_check_member() was currently sure to recognize the size of
"enum" type members in struct/union as the size of "int" even if
its size was packed.
This patch fixes BTF enum verification to use the correct size
of member in BPF programs.
Fixes: 179cde8cef ("bpf: btf: Check members of struct/union")
Signed-off-by: Yoshiki Komachi <komachi.yoshiki@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/1583825550-18606-2-git-send-email-komachi.yoshiki@gmail.com
- Allow BPF_MODIFY_RETURN attachment only to functions that are:
* Whitelisted for error injection by checking
within_error_injection_list. Similar discussions happened for the
bpf_override_return helper.
* security hooks, this is expected to be cleaned up with the LSM
changes after the KRSI patches introduce the LSM_HOOK macro:
https://lore.kernel.org/bpf/20200220175250.10795-1-kpsingh@chromium.org/
- The attachment is currently limited to functions that return an int.
This can be extended later other types (e.g. PTR).
Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200304191853.1529-5-kpsingh@chromium.org
When multiple programs are attached, each program receives the return
value from the previous program on the stack and the last program
provides the return value to the attached function.
The fmod_ret bpf programs are run after the fentry programs and before
the fexit programs. The original function is only called if all the
fmod_ret programs return 0 to avoid any unintended side-effects. The
success value, i.e. 0 is not currently configurable but can be made so
where user-space can specify it at load time.
For example:
int func_to_be_attached(int a, int b)
{ <--- do_fentry
do_fmod_ret:
<update ret by calling fmod_ret>
if (ret != 0)
goto do_fexit;
original_function:
<side_effects_happen_here>
} <--- do_fexit
The fmod_ret program attached to this function can be defined as:
SEC("fmod_ret/func_to_be_attached")
int BPF_PROG(func_name, int a, int b, int ret)
{
// This will skip the original function logic.
return 1;
}
The first fmod_ret program is passed 0 in its return argument.
Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200304191853.1529-4-kpsingh@chromium.org
Fix the following sparse warning:
kernel/bpf/btf.c:4131:5: warning: symbol 'btf_check_func_type_match' was
not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Hongbo Yao <yaohongbo@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200210011441.147102-1-yaohongbo@huawei.com
Fix the way modifiers are skipped while walking pointers. Otherwise second
level dereferences of 'const struct foo *' will be rejected by the verifier.
Fixes: 9e15db6613 ("bpf: Implement accurate raw_tp context access via BTF")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20200201000314.261392-1-ast@kernel.org
Instead of using a locally defined "struct bpf_verifier_log log = {}",
btf_struct_ops_init() should reuse the "log" from its calling
function "btf_parse_vmlinux()". It should also resolve the
frame-size too large compiler warning in some ARCH.
Fixes: 27ae7997a6 ("bpf: Introduce BPF_PROG_TYPE_STRUCT_OPS")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200127175145.1154438-1-kafai@fb.com
When accessing the context we allow access to arguments with
scalar type and pointer to struct. But we deny access for
pointer to scalar type, which is the case for many functions.
Alexei suggested to take conservative approach and allow
currently only string pointer access, which is the case
for most functions now:
Adding check if the pointer is to string type and allow access to it.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200123161508.915203-2-jolsa@kernel.org
